金属学报
Volu扣ne 27SeriesB1991AUTHOR INDEX CCAO Guanghan(曹光旱)············……6一B科6CAo weijie(曹卫恋)..················……5一B32oCAO Yilin(曹益林)··················……6一B443CHANG Xin(常听)···············……1一B48CHE Guang邻n(车广灿)·············一6一B科0CHEN Erbao(陈二保)···············……6一B410CHEN Jia....
关键词:
袁训锋
,
丁雨田
材料导报
采用Tong和Beckermann等提出的耦合流场相场模型对纯镍凝固中多晶粒枝晶的生长过程进行模拟,研究了多晶粒枝晶的生长形貌和温度分布.结果表明,熔体流动显著改变凝固前沿的传热,从而影响枝晶生长.受熔体流动和多晶粒之间相互影响的共同作用,枝晶在4个最优生长方向上的形貌呈现不对称;熔体流动还改变了枝晶的水平最优生长方向,使得水平主枝向上游倾斜;此外,二次枝晶出现径向熔化和轴向熔化等粗化方式.
关键词:
相场法
,
强制对流
,
多晶粒
,
凝固
Author X.A. Zhang1)
,
H.Q. Xia1)
,
Z.T. Wu1)
,
Y.F. Han1)
,
R. Shi2) and G.X. Hu2) \= 1) Mechanical Properties Laboratory
,
Beijing Institute of Aeronautical Materials
,
Beijing 100095
,
China2) The State Education Commission Open Research Laboratory for High Temperature
金属学报(英文版)
Materials and Testing, Shanghai Jiao Tong University, Shanghai 200030, ChinaManuscript received 18 October 1998 The threestage creep behavior of DD3 single crystal superalloy had been studied. The results show that the creeprupture properties of DD3 single crystal satisfy the requirements for high performance turbine blade application. The influence of crystal orientation on the creeprupture property of DD3 single crystal was tested and discussed. An engineering criterion to evaluate the regimes of secondary and tertiary creep is proposed, and this method gives a reasonable result for practical applications. The fractography and TEM micrography of the tested specimens had been studied, and it is determined that the glidecontrolled creep is the basic creep mechanism of DD3 single crystal at intermediate temperature, but the thermally activated processes become dominant at higher temperature.
关键词:
threestage creep curve
,
null
,
null
,
null
Journal of the American Chemical Society
In this communication, we demonstrate nonmetal SiO(x) nanoparticles (NPs) can tailor few-layer graphenes (FLGs) into graphene nanoribbons (GNRs) and regular pieces with smooth edges. The tailoring of graphene is realized by the movements of SiO(x) NPs along the graphene lattice in the atmosphere of H(2), and the tailored trenches exhibit high selectivity of the crystallographic orientation compared to the reported metal. NPs. The low tailoring rate and the tong lifetime provide great potential for accurate control of the trench length or the length of the tailored GNRs. As a result, smooth GNRs with a length of several micrometers and a width narrower than 10 nm are obtained. A catalytic hydrogenation mechanism is proposed for the tailoring of graphene by SiO(x) NPs. These findings open up the possibility for atomically precise graphene device fabrication without metal, contamination and indicate the potential catalytic activity of nonmetal Nips for the hydrogenation of carbon materials.
关键词:
nanoribbons;hydrogenation;graphite
付强
,
孔繁荣
,
陈庆国
复合材料学报
为了研究海洋能电机主绝缘材料耐盐雾湿热老化能力,对电机多胶模压(Resin Rich Molding,RRM)桐马环氧玻璃丝粉云母(Tong ma Epoxy Glass Fiber Power Mica,TEGM)绝缘材料进行模拟海洋气候的盐雾湿热老化试验,测试了不同老化周期下材料的吸水率变化,并结合扫描电子显微镜(Scanning Electron Microscope,SEM)的观测结果分析了材料老化前后微观形貌的变化.利用宽频介电阻抗谱仪测试不同老化周期和不同测试温度下的TEGM绝缘材料的频域介电参数变化,并运用电介质极化理论分析老化前后的微观结构形态变化和宏观介电性能之间的关系.研究结果表明,TEGM绝缘试样老化过程中的吸水性呈现快速吸湿、缓慢吸湿和饱和吸湿3个阶段;随着老化时间的延长,材料相对介电常数和介质损耗因数呈上升趋势,利用频域介电谱(Frequency Domain Spectroscopy,FDS)曲线可较好反映绝缘材料的老化状态;通过对测试数据的拟合,得到老化绝缘材料的介电参数与材料吸水率在低频下存在的二次方程关系.
关键词:
盐雾湿热老化
,
频域介电谱
,
多胶模压
,
桐马环氧玻璃丝粉云母
,
绝缘材料
,
老化
,
吸水率
